> I need to be able to switch between an on-board LCD and
> eight external I/O lines

If you're using the 8 I/O as LCD 0-7 then you might not need a
switch. Include a diode and resistor in each external line. When
you want to drive the LCD, set the port to o/p, when you want
to read the external I/O, set it to i/p (taking into account the LCD's
Busy). You could also make the LCD interface 4-bit to reduce
the D-R to 4 each

If you have to use a buss switcher, you need only one, as the
external data can appear on the LCD datalines. It won't get
written without flicking E, and LCD i/ps have weak pull-ups,
so they won't float when the micro port is i/p. Although they'll
be being driven by the external I/O anyway

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